The present invention concerns an organogel containing composition, the organogel being largely composed of a liquid fatty component and a mixture of sterols.
The organogel of the invention has a firmness larger than that of the liquid fatty component when compared at the same temperature, normally room temperature. The liquid fatty component is herein referred to as liquid fat. Fats are commonly applied in a wide range of consumer products, including food and cosmetic products, and also in technical, non-consumer areas. In many of such applications, it is desired that the product comprising the liquid fat has some structure or firmness, meaning that the product is not as liquid and pourable as the liquid fat itself when comparing at similar conditions. Several methods are used for providing structure, the use of solid fats in addition to the liquid fat being one of the most commonly applied. In applications where in addition to the fat, also a non-fatty liquid, such as water, is present, also emulsifiers and/or thickeners and/or gelling agents are applied, so that the non-fatty liquid adds significantly to the firmness of the end product. In most applications, and in particular in compositions comprising high amounts of fat, solid fat is applied for structuring (or giving firmness to a products) for technical and practical reasons, in particular in fat continuous products comprising >50% of fat, preferably >60% of fat. At lower fat levels, a combination of solid fat, emulsifiers and thickeners and/or gelling agents is often used. However, in consumer products, in particular in food products, there is an increased desire to reduce or even do without the presence of solid fats for various reasons. For example, such reasons can be based on health concerns, as were fat is consumed, the consumer desires products with saturated fatty acid (SAFA) levels as low as possible, and, preferably, with low trans fatty acid levels (e.g., less than 4%). More preferred, fat containing products are even free of any trans fatty acid levels. Drawbacks sometimes have to do with increase of costs, and/or negative consumer perception of the ingredients used.
Thus, in one embodiment of the present invention, a method is found to replace part or all of the solid fat in a fat composition composed of solid fat alone or of a mixture of solid and liquid fat, by the use of an organogel as claimed herein. Alternatively, the invention is suitable for the reduction of the structuring material necessary to give firmness to the liquid fat containing composition. Another object of the present invention is to provide a new method for giving firmness to a liquid fat, in particular to a glyceride, without chemical modification. In the present application, a liquid fat means that the liquid fat is pourable at the temperature its application is envisaged. For most products, and in a preferred embodiment, this means at room temperature (20° C.). Examples of such liquid fats include liquid paraffins and liquid, organic fatty components as often applied in consumer products, for example polyol esters like mono-, di- and triglycerides.
The present invention now provides a composition comprising an organogel, the organogel being largely composed of a liquid fatty component, at least one sterol and at least one sterol ester. It is desired that both are present in an amount of at least 1 wt % each, based on the total amount of liquid fat used in the organogel. Preferably, all liquid fat present in the composition of this invention is formed into an organogel. In a particular embodiment the organogel comprises at least 75% liquid fat. In one embodiment of this invention, the composition claimed consists of an organogel composed of a liquid fat, a sterol (or mixture of different sterols) and a sterol ester (or mixture of different sterol esters). In another embodiment, other components are present as well. Preferably, the composition does not comprise water. Accordingly, the organogel of the present invention can be used in combination with other component, such as solid fat, with water, or combinations thereof, and may comprise any other component commonly applied and depending on the end use desired. Preferably, no components are used which negatively affect the firmness of the organogel itself. It is further preferred that in compositions in which water is present and for which a firmness of the organogel is still desired after a prolonged storage time, additional measures are taken. As an example, it is desired to used components which reduce the water activity. Thus, in the present composition, still solid fat can be present. For example, in a prior art composition composed of liquid and solid fat, the amount of solid fat can be reduced by the use of a mixture of sterol composed as envisaged in the present invention. In this embodiment it is preferred that not only part or all solid fat is replaced by liquid fat, but that all liquid fat in the composition is present in the form of an organogel. In a highly advantageous embodiment, the composition consists of an organogel and solid fat. It is preferred to use solid fat having a low SAFA level, say less than 10%, and a trans fatty acid level of less than 4%, preferably the solid fat being virtually free of trans fatty acids. As indicated above, in the composition of one of the embodiments of the present invention, other components commonly applied in the composition envisaged can be present. For example, in a margarine type of product, all or part of the solid fat present can be replaced by the organogel, and in addition, other components commonly present in such margarine type products such as solid fat, water, flavours, salt, and the like, can be present. In this specification, a sterol is a polycyclic alcohol, with at least 24 carbon atoms and at least 4 condensed rings, with a ring size of at least 3 atoms, preferably a ring size in the range of 3-6 atoms. In a preferred embodiment, the rings are almost planar ring systems such as found in cholesterol. In a further preferred embodiment, the hydroxyl groups (or C—O bonds) are positioned in the same plane as the ring system, i.e. equatorial and not axial. Sterol esters are, in this specification, esters of phenolic acids of the sterols defined above. The term phenolic acids relates to the family of cinnamic acids, of which caffeic acid and ferulic acid are examples. Very good results were obtained when the esterified sterol has a structure highly similar to that of the free sterol applied. In one particularly preferred embodiment, the free sterol is a ferulic acid, and the phenolic acid esterified sterol is a ferulic acid sterol ester. At present, it is believed that the free sterol or a component of similar chemical structure, and the phenolic acid esterified sterol or a component of similar chemical structure, tend to form aggregates when dissolved in the liquid and that these aggregates show a certain level of network formation or even polymerization in the liquid, which is then reflected in a structuring of the liquid. Hence the structuring of the liquid would resemble the formation of a gel known from aqueous gels. However, applicant does not wish to be bound by this theory. Examples of suitable combination of sterols and sterol esters selected from the group of phytosterols are oryzanol and sitosterol (often denoted by β-sitosterol). Also cholesterol is found to be a suitable component that can provide structure to a liquid fatty component when applied at specific levels in combination with other phytosterols.
An additional advantage of the present invention is found in that most of the sterols applicable for providing structure according to the present invention are components obtainable from natural sources. In a preferred embodiment of the invention, the sterols and/or sterol esters applied are components which can also be found in nature. For example, oryzanol and sitosterol are present as minor components in many plants. In quite some cases, these are even present in the plants from which triglycerides are obtained. It is to be noted, however, that the sterol (ester) components are not present in amounts sufficient to provide structuring in these natural sources, nor are these present in the mole ratios needed for obtaining sufficient structure. Also, in many cases, not all sterols needed for the structuring are present in the plants from which the oils are obtained. At present, these minor components are often partially removed during oil refining. Hence, one of the objects of the present inventions is to provide a new method for giving firmness to a liquid fat, in particular to an edible glyceride, without chemical modification of any of the ingredients being needed.
In particular, sterols and sterol esters found to be highly suitable for providing hardness to the liquid are selected from the group of phytosterols. In this invention the term phytosterol is used to cover the whole group of free phytosterols, phytosterol fatty acid esters and (acylated) phytosterol glucosides. There are three major phytosterols, namely beta-sitosterol, stigmasterol and campesterol. Schematic drawings of the components meant are as given in “Influence of Processing on Sterols of Edible Vegetable Oils”, S. P. Kochhar; Prog. Lipid Res. 22: pp. 161-188. Sitosterol can, for example, be obtained from wood and from refining vegetable oil, and normally comprises also a minor amount of other sterols, like campesterol, stigmasterol, various avenasterols etc. For the present invention, it is not needed that the sterols and/or sterol esters used are highly pure; some impurities can be present, it is considered not to be of concern in particular, when the polarityiis relatively low.
Oryzanol consist of a mixture of ferulic acid esters of unsaturated triterpene alcohols and is also referred to as gamma-oryzanol. In this invention only the term oryzanol is used. For a further description and schematic drawing of oryzanol, reference is made to “Separation of Vitamin E and gamma-Oryzanols from Rice Bran by Normal-Phase Chromatography”, M. Diack and M. Saska, JAOCS Vol. 71, no. 11, pp. 1211. Oryzanol can, for example, be obtained from ricebran, and comprises ferulic acid esters of several phytosterols. Cholesterol is, for obvious health reasons, less desired when the use of in food products is envisaged. For any other of the applications, however, it may be very well applicable. A highly suitable combination, in particular for food products, was found in the use of both oryzanol and sitosterol.
The organogel of the invention has a firmness larger than that of the liquid fat when compared at the same temperature, normally room temperature. In a highly preferred embodiment, firmness of the organogel consisting of liquid oil and a mixture of sterol and sterol esters according to the invention has a Stevens 4.4 hardness (“Stevens 4.4” value) of at least 20 grams measured at 20° C. The Stevens hardness St, expressed in grams, is determined 1 week after manufacturing the organogel when stored at 5° C. and thereafter equilibrated for 24 hours at the temperature as indicated, using a 4.4. mm. diameter cylinder in a Stevens—LFRA Texture Analyzer (ex. Stevens Advanced Weighing Systems, UK) load range 1000 g operated “normal” and set at 10 mm penetration depth and 2.0 mm/s penetration rate.
Thus, Stevens hardness is for this purpose considered a parameter sufficient to distinguish between the liquid fat and the “structured” liquid fat (the organogel).
The mixture of the sterol(s) and sterol ester(s) of the invention are capable of structuring a liquid fat when added to a liquid fat in an amount of at least 1 wt % each, based on the amount of liquid fat. The sterols and sterol esters have a limited solubility in liquid fat, the saturation point depending on the specific components used. In most cases, the amount sufficient for structuring is the level whereby all structure providing sterols and sterol esters are added at a total level equal or preferably, above the saturation point of the solution. In particular, the minimum total amount of sterols (i.e. sterols+sterol esters) is at least 2 wt % and preferably 3 wt %, based on the total amount of liquid fat present in the composition. The sterols and sterol esters are dissolved in the liquid fat, and it is believed, without wishing to be bound by theory, that the structuring is obtained by the sterols and sterol esters which are added at a level above the saturation of the solution, meaning that these are the not-dissolved sterols which are believed to provide the structure to the liquid. It was found that the molar ratio of sterols and sterol esters should be in the range of 1:10-10:1, preferably 1:5-5:1, whereby a preference exist for 1:3-3:1, towards almost equal molar ratio's, as it was found that an optimal structuring effect was obtained for providing firmness to a liquid fat, in particular a liquid triglyceride.
In one particular and preferred embodiment of the invention, the liquid fat is overall apolar. Surprisingly, it was found that almost all apolar liquid fats can be given firmness by the use of a combination of a sterol (mixture) and a sterol ester (mixture), which preferably is the ester of the specific sterol (mixture) used. The invention is in particular advantageous in the foods area, so that the use of edible liquid fat and edible sterol(s) and edible sterol ester(s) is preferred. Thus, for food products, the liquid fat is an edible fat, and the sterols used is a mixture of phytosterols, preferably oryzanol and sitosterol at a minimum total weight level of 2%, preferably 4%, with a clear optimum at a molar ratio between 3:1 and 1:3, further preferred between 1:2 and 2:1. After dissolution of the sterols in the fatty compound at elevated temperature, improvement of structuring capacity of the sterols was found by rapid cooling.
In a further preferred embodiment for food products, it was found that sitosterol and oryzanol provide significant and sufficient structure to an edible liquid acyl glyceride when both are present in a total amount of at least 2 wt % each, based on the liquid acyl glyceride fat. An optimum in providing hardness to a product was found in the use of oryzanol and sitosterol in about equal molar ratio in combination with the use of a liquid polyol ester, preferably a mono-, di- and/or triacyl glyceride. In addition thereto, the use of sitosterol and oryzanol in food products are nowadays believed to add beneficial health effects upon their daily intake, in particular with respect to a reduction of coronary heart diseases. For many applications, and in particular for food, the use of edible liquid acyl glycerides, in particular triacyl glycerides is preferred as the liquid fatty component. As suitable triacyl glycerides, fats and oils (here used as synonyms) both vegetable and animal fats obtained from natural and synthetic origin can be used. Preferred are liquid vegetable and/or animal fats obtained from natural sources. It is further preferred that these oils comprise a substantial amount of C14 to C22 glycerides, and further preferred a substantial amount of glycerides having C16-C20 triglycerides. The C-numbers refer to the number of carbon atoms per fatty acid group
In another preferred embodiment, the liquid fatty compound comprises a substantial amount of saturated acyl glycerides, in particular saturated triglycerides, as the use thereof was found to be beneficial with respect to the hardness of the product. It was observed that a further increased amount of the structuring sterols is desired for compositions comprising high levels of unsaturated acyl glycerides compared to the levels needed for the same degree of structuring. The less unsaturated glycerides were used, the harder the product with a same amount of sterols present. In food products, it may be desired for health reasons, however, to use less saturated glycerides and a higher amount of sterols. The vegetable triglycerides often used in consumer products include those obtained from seeds, beans, fruits and nuts, or parts of these plant materials such as their germs, and are often obtained by mechanical expelling and/or solvent extraction. Examples of liquid triglycerides which are in particular suitable for use in the present invention are sunflower oil, rapeseed oil, flax or linseed oil, soybean oil, maizegerm or corn oil, wheatgerm oil, ricebran oil, palm oil, olive oil peanut oil, and the like. Also, oils of animal origin can be used in the present invention, and include those obtained from processing fish, for example, fish oil. Other liquid fats that can be applied in the present invention comprise or consist of sucrose polyol polyesters.
Within the scope of the present invention is a composition according to the main claim, in which the fat applied is a fat which is not liquid at room temperature. The term liquid fat regards fat which is liquid at the temperature applied. For example, fats can be applied at temperatures higher than room temperature whereby it is still desired that the fat at its application temperature is not liquid, but has some structure. As is well known, most fats melt at their heating, and also above there melting temperature they can be structured by means of the sterols as presently envisaged within the present invention. It will still be desired to use an amount at or above the level of saturation at the envisaged application temperature. Preferably, temperature of application of the organogel containing composition is less than 80° C., as it was found that the organogel becomes less stable at temperatures higher than that.
In another embodiment of the invention, a liquid fat or oil of vegetable or animal source is used as indicated above, to which, in addition to the sterols, at least 1 wt % based on the amount of liquid fatty compound used, of monoglycerides is added. It was found that an additional increase of hardness is obtained by the addition of 1% or more, e.g. 2-10% of monoglyceride, or that a reduction of the amount of sterols needed to obtain hardness or viscosity for the liquid fatty compound by the addition of a monoglyceride.
The composition according to the present invention can be prepared by the simple dissolution of the sterol(s) in the liquid fat. For example, a composition of significant hardness compared to the liquid itself is obtained by dissolving a phenolic acid ester of a sterol and a sterol by mixing the ingredients and stirring at elevated temperatures. For many fats and oils, a temperature of more than e.g. 40-50° C., often more than 75° C. or 85° C. will be sufficient, in some cases 90° C. degrees is desired in order to achieve rapid dissolving. As soon as a clear, transparent solution is obtained the liquid solution can be allowed to cool to, for example, ambient temperature. The formation of the structured system often proceeds rather slowly, and for some cases, it can take more than one day up to several days before the ultimate degree of structuring is achieved. It was found that a more rapid and even instantaneous structuring of the solution is obtained by applying rapid cooling. A very suitable means therefore is a surface scraped cooling device, for example a votator (A-unit).